Stapling device

Abstract

A staple wire cutting element (4) is mounted displaceably on a stapling device (1) in which staple wire segments are shaped into a staple and driven into a sheet stack. A control lever (8) that is in engagement with a radial cam unit (6) engages the cutting element (4). The radial cam unit (6) is driven via an overrunning clutch (10), one end of which has a gear (11) which is fixed to the radial cam unit (6) and engages into a gear (5b) of a stepping motor (5). The other end of the overrunning clutch (10) has a gear (12) which is fixed to a transport wheel (13) for staple wire transport. A gear (27), which is mounted displaceably along its rotation axis and is mounted rotatably about the same rotation axis as the gear (5a), engages into the gear (12). The gears (5b, 27) are equipped at their sides facing one another with tooth sets (28). For backward transport of the wire segment which is ready for staple shaping, the displaceable gear (27) is brought into engagement with the gear (5b), thus allowing the wire to be transported backward, bypassing the overrunning clutch (10).

What is claimed is: 
     
       1. Stapling device for stapling a stack of sheets by staples that are cut off from a staple wire supply and shaped in the stapling head region, said stapling device comprising: a staple wire transport device which transports staple wire a corresponding length as a function of the thickness of a sheet stack to be stapled;   a movable staple wire cutting element which positions staple wire, as a function of the thickness of the sheet stack to be stapled, centrally with respect to a staple shaping element on the stapling head;   said staple wire transport device driven by a stepping motor whose drive direction is reversible and which is activated by a measuring device which determines the thickness of the stack to be stapled;   said stepping motor coupled to said staple wire transport device by a coupling that is effective only in a staple wire transport direction;   said stepping motor continuously coupled to a movable cam unit which controls a displacement of said staple wire cutting element; and   said cam unit includes control segments which are associated with different sheet stack thicknesses, said cam unit being rotatably mounted on a shaft and having two gears, mounted rotatably about said shaft and joined to one another via an overrunning clutch, one gear of said two gears being rigidly joined to said cam unit, and in engagement with a non-axially displaceable gear of said stepping motor, the other gear of said two gears being rigidly joined to a staple wire transport wheel and in engagement with a gear which is mounted displaceably axially with respect to said non-axially displaceable gear, and said axially displaceable gear being selectively brought into positive engagement with said non-axially displaceable gear.   
     
     
       2. Stapling device as defined in claim 1, wherein said gears are equipped with a non-axially displaceable and said axially displaceable gear set on their sides facing one another. 
     
     
       3. Stapling device as defined in claim 1, wherein a preloaded pressure spring is arranged between said non-axially displaceable and said axially displaceable gears. 
     
     
       4. Stapling device as defined in claim 1, wherein said displaceable gear is movable by an angled lever joined to a reciprocating magnet and engaging on said gear.